Method and apparatus for making inner tubes or the like



Jan. 19 1%32. ,3, R GAPIQMETER 1,841,886

METHOD AND APPARATUS FOR MAKING INNER TUBES OR THE LIKE Filed Feb. 5, 1929 2 Sheets-Sheet 1 I N VEN TUR. joy/v I? Qswlyfree A TTORNEYS.

J. R. GAMMETER METHOD AND APPARATUS FOR MAKING INNER TUBES OR THE LIKE Jan. 19, 1932.

Filed Feb. 5, 1929 2 Sheets-Sheet 2 INVENTOR ATTORNEYS.

Patented Jan. 19, 1932 rnrnr METHOD AND APPARATUS FOR MAKING INNER TUBES OR THE LIKE Application filed February 5, 19. 29.

This invention relates to methods for making inner tubes for pneumatic tires and to apparatus for use in carrying out such methods.

It has heretofore been proposed to make inner tubes from water dispersions or solutions of rubber, for example, natural rubber latex, by depositing latex on a circular form of mandrel, either by dipping, electro-deposition, etc., but these methods have not been entirely successful owing to the chiliculty in removing the finished tubes from the forms.

The present invention has for its object a method for making inner tubes by depositing rubber on mandrels or forms whereby they are easily removed from the mandrels or forms either while raw or vulcanized, and also the provision of a mandrel or form so constructed as to permit easy removal of the tube therefrom. Y

The foregoing and other purpose of the invention are attained by the method and the mandrel or core construction illustrated in the accompanying drawings and described below. It is to be understood that the invention is not limited to the specific form thereof shown and described.

Of the accompanying drawings,

Figure 1 is an elevation of a mandrel or core embodying the invention;

Figure 2 is a section on line 22 of Figure 1; I

Figure 3 is a part plan of the core atthe split;

Figure 4 is an elevation of the core showing the initial operation in removing an inner tube of deposited rubber therefrom;

Figure 5 is a section on line 55 of Figure 4:; V

Figure -6 is a view similar to Figure at showing the tube in an intermediate stage of removal;

Figure 7 is an end view thereof;

Figure 8 is a view similar to Figures 4 and 6 showing the tube in the final stage of removal;

Figure 9 is a plan of the completed tube at the valve patch on line 9-9 of Figure '10; and

Serial No. 337,576.

FigurelO is a section on line lO-10 of Figure 9 through the completed tube at the valve patch.

Referring to the drawings, the numeral 11 designates a circular mandrel or core preferably of metal and preferably formed of dumb-bell or other non-circular shape in radial section as shown so that when a tube is formed thereon and inflated or expanded as by air or other fluid medium under pressure, its friction on the core will be greatly reduced (see Figure The core 11 is formed with a slit therethrough at 12 at an angle preferably approximating with respect to both the radial section and the vertical plane of the core, and an arm l1" is provided to support the core from the inner periphery adjacent said slit. The core preferably is set in a helical or screwdike formation so that normally the faces of the slit 12 are separated as shown in the Figure 3 sufficiently to permit slippingof a wall of the inner tube through the slit. Means may be provided comprising a bolt 13 extended from adjacent the inner periphery of the core preferably through arm 11 through a bore 14 in the core at one side of the split and threaded into a bushing member 15 secured in a bore 16 through the core on the other side of the slit, the bolt being perpendicular to the faces of the slit for drawing the faces of the slit together and thus holding the core in circular form while the rubber is being deposited thereon. The bushing member 15 at its outer end is so formed as to plug the end of the bore on the outer side of the core, the outer surface of the bushing following the curvature of the core. The arm 11 may be mounted on a central shaft 11 by which the core may be rotated as the rubber is deposited thereon.

In practicing the method, rubber is deposited on the core either by dipping as by retating the core one or more times through a water dispersion or solution of rubber together with any desired compounding or vulcanizing ingredients or by electro-deposition or coagulation of rubber from a water dispersion onto the core while rotated through the dispersion or otherwise until the desired thickness of rubber has been built upon the core to form the tube 17. The rubber is dried on the core in any suitable way preferably by heat applied from within the core either by fluid mediums conducted into the core, electrical resistance units placed in the core, or by induction methods in which the core is placed in a transformer circuit.

As will be apparent the arm 11 causes an opening to be formed in the inner periphery of the tube at 18 and this may be shaped in section as to provide an opening in the tube sufficiently large to permit its being stretched to pass about the core and over which the valve patch of the inner tube can be applied when the tube is removed from the core.

If it is desired to vulcanize the tube while on the core this can be done by a number of known methods such as by curing the rubber with a fluid curing medium such as hot water preferably under pressure about the core. in this case, patch 20 may be later applied over the opening 18 being cemented and vulcanized to the tube, the valve 21 being previously inserted in the tube and subsequently extended through and clamped to the patch as will be understood. The tube also may be removed from the mandrel while raw, the valve 21 inserted, patch 20 applied, and the valve being secured in the patch and the whole assembly vulcanized under internal pressure in an inner tube mold of any desired type. The rubber may also be deposited from vulcanized dispersions or solutions onto the forms.

In any case the removal of the tube from the mandrel is accomplished as illustrated in Figures 4 to 8 inclusive. The bolt 13 is withdrawn, permitting the mandrel to return to its set helical form with the faces of the split 12 separated. Air or other fluid medium under pressure from a hose and nozzle such as'has been used for a great many years in stripping rubber tubes from mandrels may be utilized to conve a lubricant such as soapstone into the tu e through opening 18 about the mandrel to loosen the tube from the core as illustrated in Figure 5. The opening 18 is then stretched so as to pass about the end of the mandrel supported by arm 11 as shown in Figure 4. Then referably while still injecting air or other uid medium between the tube and mandrel, the tube is slipped about the mandrel, in effect, screwed off the other end of the mandrel, the wall of the tube passing through slit 12 as shown in Figures 6, 7 and 8, the opening passing off said other end of the mandrel as the stripping is completed as will be apparent from Figure 8.

To prepare the mandrel for use in making another inner tube, the bolt 13 is reinserted, drawing the faces of the slit 12 together and holding the core again in circular form.

It will be apparent from the foregoing that simple, but effective apparatus and procedure have been provided for making inner tubes of deposited rubber. Obviously modifica tions of this invention may be resorted to without departing from the spirit thereof or the scope of the appended claims.

What is claimed is 1. That method of making inner tubes of rubber comprising depositing rubber on a core or mandrel of non-circular shape in radial section and split so that it may assume either an endless formation or a helical formation, said rubber being deposited on the mandrel while it is in endless format-ion, makipg an opening in the tube of rubber thus form injecting fluid carrying a lubricant between the tube and mandrel through said opening to expand the wall of the tube away from the surface of the mandrel, spreading the split to cause the mandrel to assume its helical formation, stretching the opening throu h the split about one end of the mandrel, s iding the tube about the mandrel from said end to the other end thereof while maintaining fluid between the tube and mandrel to remove the tube from the mandrel, inserting a valve through the opening into the tube, applying a valve patch over said opening, securing said valve in position in the patch with the stem thereof extending through the patch, and vulcanizing the tube in a mold under internal pressure.

2. That method of making inner tubes of rubber comprising depositing rubber on a core or mandrel of non-circular shape in radial section and split so that it may assume either an endless formation or a helical formation, said rubber being deposited on the mandrel while it is in endless formation by rotating the mandrel in a rubber dispersion, forming an opening in the tube of rubber during the depositing of the rubber in the mandrel, injecting fluid carrying a lubricant between the tube and mandrel through said opening to expand the wall of the tube away from the surface of the mandrel, spreading the split to cause the mandrel to assume its helical formation, stretching the opening through the split about one end of the mandrel, sliding the tube about the mandrel from said end to the other end thereof while maintaining fluid between the tube and mandrel to remove the tube from the mandrel, and vulcanizing the tube.

3. That method of making inner tubes of rubber comprising depositing rubber on a core or mandrel of dumbbell shape in radial section and split so that it may assume either an endless formation or a helical formation, said rubber being deposited on the mandrel while it is in endless formation, making an opening in the tube of rubber thus formed, injecting fluid carrying a lubricant between the tube and mandrel through said opening to move the wall of the tube away from the surface of the mandrel so that due to the shape of the mandrel the circumference thereof is less than that of the tube, spreading the split to cause the mandrel to assume its helical formation, stretching the opening through the split about one end of the mandrel, and sliding the tube about the mandrel from said end to the other end thereof while maintaining fluid betwen the tube and mandrel to remove the tube from the mandrel.

4:. That method of making inner tubes of rubber comprising depositing rubber on a core or mandrel of non-circular shape radial section and split so that it may assume either an endless formation or a helical formation, said rubber being deposited on the mandrel while it is in endless formation, making an opening in the tube of rubber thus formed, injecting fluid between the tube and mandrel through said opening to move the wall of the tube away from the surface of the mandrel without stretching the tube, spreading the split to cause the mandrel to assume its helical formation, stretching the opening through the split about one end of the mandrel, sliding the tube about the mandrel from said end to the other end thereof wnile maintaining fluid between the tube and mandrel to remove the tube from the mandrel, and vulcanizing the tube.

5. That method of making inner tubes of rubber comprising depositing rubber on a core or mandrel of non-circular shape in radial section and split so that it may assume either an endless formation or a helical formation, said rubber being deposited on the mandrel while it is in endless formation, making an opening in the tube of rubber thus formed, injecting fluid between the tube and mandrel through said opening to move the wall of the tube away from the surface of the mandrel without necessitating the stretching of the tube, spreading the split to cause the mandrel to assume its helical formation, stretching the opening through the split about one end of the mandrel, and sliding the tube about the mandrel from said end to the other end thereof while maintaining fluid between the tube and mandrel to remove the tube from the mandrel.

6. A mandrel for making inner tubes of deposited rubber, said mandrel being split substantially at an angle of 45 to both its radial section and its vertical plane and normally formed to assume a helical shape with the faces of the split slightly separated to permit passing of the wall of an inner tube therethrough, an arm supporting the man drel from its inner periphery adjacent the split, said arm being adapted to be secured on a shaft to rotate the mandrel and adapted to form a valve opening in the inner periphery of the tube, and a bolt adapted to be extended through the arm and one end of the mandrel and threaded into the other end of the mandrel to draw the mandrel into endless shape with the faces of the split together.

7. A mandrel for making inner tubes of deposited rubber, said mandrel being split and normally formed to assume a helical shape with the faces of the split slightly separated to permit passing of the wall of an inner tube therethrough, an arm supporting the mandrel from its inner periphery adjacent the split, said arm being adapted to be secured on a shaft to rotate the mandrel and adapted to form a valve opening in the inner periphery of the tube, and means for drawing the faces of the slit together.

8. A mandrel for making inner tubes of deposited rubber, said mandrel being split substantially at an angle of 45 to both its radial section and its vertical plane and normally formed to assume a helical shape with the faces of the split slightly separated to permit passing of the wall of an inner tube therethrough, and a bolt adapted to be eX- tended through the arm and one end of the mandrel and threaded into the other end of the mandrel to draw the mandrel into endless shape with the faces of the split together.

9. A mandrel for making inner tubes of deposited rubber, said mandrel being split and normally formed to assume a helical shape with the faces of the split slightly separated to permit passing of the wall of an inner tub-e therethrough, and means for drawing the faces of the slit together.

10. That method of making inner tubes on a mandrel dumb-bell shape in cross-section and split so that it may assume either an endless formation or a helical formation comprising depositing rubber on the mandrel when it is in endless formation, making an opening in the tube of rubber thus formed, injecting fluid through the opening to move the tube from dumb-bell shape to substantially circular shape, spreading the split to cause the mandrel to assume its helical formation, stretching the opening through the split about one end of the mandrel and sliding the tube about and off the mandrel.

11. That method of making tubes on a dumb-bell shaped mandrel split so that it may assume either an endless formation or a helical formation comprising depositing rubber on the mandrel when it is in endless formation, making an opening in the tube of rubber thus formed, injecting fluid through the opening to move the tube from dumb-bell shape to substantially circular shape, spreading the split to cause the mandrel to assume its helical formation, stretching the opening through the split about one end of the mandrel and sliding the tube about and off the mandrel.

12. That method of making inner tubes on an annularly grooved mandrel split so that it may assume either an endless formation or a helical formation comprising depositing rubber on the mandrel when it is in endless tlformation, making an opening in the tube of (8 rubber thus formed, in]ecting fluid through the opening to move the tube from the annularly grooved contour of the mandrel to substantially circular shape, spreading the split to cause the mandrel to assume its helical m formation, stretching the opening through the split about one end of the mandrel and sliding the tube about and off the mandrel. JOHN R. GAMMETER. 

